EFFECTS OF SEAT POSITION ON JOINT LOADS OF THE UPPER EXTREMITIES DURING HANDCYCLING IN WHEELCHAIR-DEPENDENT INDIVIDUALS

The current study aimed to quantify the joint moments of the upper extremities with different seat positions during handcycling in wheelchair-dependent individuals. Sixteen subjects performed handcycling while the handgrip reaction forces were measured by a handgrip instrumented with a six-component load cell and body segment kinematic data by a motion capture system. Both data sets were used to calculate joint moments of the upper limbs during a crank cycle. The loads at the shoulder were affected mostly by the vertical seat positions. The higher the seat, the greater loads transmitted by the muscles with relatively greater strength. The current data will be helpful for future handcycle design and fitting for wheelchair-dependent individuals

User Resistance to the Implementation of Information Systems: A Psychological Contract Breach Perspective

The current study proposes an exploratory model to examine the antecedents of user resistance in information system (IS) implementations from the perspective of a psychological contract breach (PCB). The purpose of this study is to investigate PCBs between users and IS providers (ISPs), which extends IS theory in two ways: by elaborating on why some users psychologically resist the IS, and by more deeply exploring the social-psychological determinants of user resistance. Our results show that user-perceived PCBs can lead to user resistance and feelings of violation via reneging, high user vigilance, and incongruence between the users’ and the ISP’s understandings of the obligations. Our results also show that users’ interpretations—i.e., causal attribution of the breach and perceived fairness after the breach—moderate the relationship between user-perceived PCBs and feelings of violation. We discuss our findings and their academic and practical implications, and suggest directions for future research

Preparation of ZnO membrane by chemical bath deposition method via regulated acidity

In this study, the chemical bath deposition (CBD) method was used to deposit a ZnO membrane on an indium tin oxide glass substrate. The deposition reaction working temperature was 90°C and the temperature retaining deposition time was 60 min; NH4OH was used to control the pH value in the range 10~11, and after deposition, the specimen was thermally annealed in air. Annealing temperatures in the range of 100~500°C were adopted to investigate the thin-film growth behavior and the effect of processing temperature on the ZnO membrane performance during the annealing process. The process parameters related to the preparation of the ZnO membrane by CBD were the pH value, retaining temperature deposition time, working temperature for the deposition reaction, annealing thermal processing, and so on. Scanning electron microscopy (SEM) was used to observe and analyze the surface morphology and microstructure of the membrane cross section, and UV-Vis spectrometry was used to measure the optical transmission of the ZnO membrane in air at different annealing temperatures. We investigated the effects of different pH values on the growth of the ZnO membrane by CBD. The experimental results show that at a pH of 10.7, we can obtain a transparent and electrically conductive ZnO thin film with a thickness of 240 nm, which has very good optical transmission and high electrical mobility at an annealing temperature of 200°C. Keywords: Chemical bath deposition, ZnO membrane, pH valu

Plasticity of cerebellar Purkinje cells in behavioral training of body balance control

Neural responses to sensory inputs caused by self-generated movements (reafference) and external passive stimulation (exafference) differ in various brain regions. The ability to differentiate such sensory information can lead to movement execution with better accuracy. However, how sensory responses are adjusted in regard to this distinguishability during motor learning is still poorly understood. The cerebellum has been hypothesized to analyze the functional significance of sensory information during motor learning, and is thought to be a key region of reafference computation in the vestibular system. In this study, we investigated Purkinje cell (PC) spike trains as cerebellar cortical output when rats learned to balance on a suspended dowel. Rats progressively reduced the amplitude of body swing and made fewer foot slips during a 5-min balancing task. Both PC simple (SSs; 17 of 26) and complex spikes (CSs; 7 of 12) were found to code initially on the angle of the heads with respect to a fixed reference. Using periods with comparable degrees of movement, we found that such SS coding of information in most PCs (10 of 17) decreased rapidly during balance learning. In response to unexpected perturbations and under anesthesia, SS coding capability of these PCs recovered. By plotting SS and CS firing frequencies over 15-s time windows in double-logarithmic plots, a negative correlation between SS and CS was found in awake, but not anesthetized, rats. PCs with prominent SS coding attenuation during motor learning showed weaker SS-CS correlation. Hence, we demonstrate that neural plasticity for filtering out sensory reafference from active motion occurs in the cerebellar cortex in rats during balance learning. SS-CS interaction may contribute to this rapid plasticity as a form of receptive field plasticity in the cerebellar cortex between two receptive maps of sensory inputs from the external world and of efference copies from the will center for volitional movements

Melatonin Therapy Prevents Programmed Hypertension and Nitric Oxide Deficiency in Offspring Exposed to Maternal Caloric Restriction

Nitric oxide (NO) deficiency is involved in the development of hypertension, a condition that can originate early in life. We examined whether NO deficiency contributed to programmed hypertension in offspring from mothers with calorie-restricted diets and whether melatonin therapy prevented this process. We examined 3-month-old male rat offspring from four maternal groups: untreated controls, 50% calorie-restricted (CR) rats, controls treated with melatonin (0.01% in drinking water), and CR rats treated with melatonin (CR + M). The effect of melatonin on nephrogenesis was analyzed using next-generation sequencing. The CR group developed hypertension associated with elevated plasma asymmetric dimethylarginine (ADMA, a nitric oxide synthase inhibitor), decreased L-arginine, decreased L-arginine-to-ADMA ratio (AAR), and decreased renal NO production. Maternal melatonin treatment prevented these effects. Melatonin prevented CR-induced renin and prorenin receptor expression. Renal angiotensin-converting enzyme 2 protein levels in the M and CR + M groups were also significantly increased by melatonin therapy. Maternal melatonin therapy had long-term epigenetic effects on global gene expression in the kidneys of offspring. Conclusively, we attributed these protective effects of melatonin on CR-induced programmed hypertension to the reduction of plasma ADMA, restoration of plasma AAR, increase of renal NO level, alteration of renin-angiotensin system, and epigenetic changes in numerous genes